[start2finish]

Okay, this shouldn't matter which brand we choose, but we have installed several walls this year and they have turned out great. I have no doubts about the base or drainage I have installed. But we spend lots of time preparing the base and laying the base course. I would like some ideas from more experieced installers.

we use 6 inches of ABC with 1/4-1/2 inch of sand. base is mechanically compacted and leveled on grade with transit. We are looking for a streamed line approach to the process. have considered using "batter boards" or form the base and screed it to our liking, but sometimes it is difficult working in a 12 inch x 30 inch trench (base and embedded block) I have a small wall to install around a pool we have built and due to the small height I would like to make it faster (18'' tall) we are including columns and fencing, bear in mind this is in the planning stages but I believe it to happen soon.

thanks for the tips,

[Matt Kulp]

Here is something that I was recently told to try by a reputable conserv rep for a large retaining wall mfg. Before this guy went to the rep. side, he owned an install company for over 20 years all he did was walls.
He told me to get your compacted base as close as you would on any other wall and then he told me to put a (2-3" thick/width of the block) bead of mortar across the the base. Lay your base course in to the desired level, and let it set for 8-10 hours. He said that the mortar will become a natural extension of the block and you do not give up any structural integrity. He said on larger walls, a crew of 3 was doing 250-300' of base course a day. I have not tried it yet, however I will be trying it in a couple of weeks.

I could see the drying time being a pain on smaller jobs, but on longer walls the time savings would be huge. This has been the biggest estimate buster in the past for us.

Like I said, I have not tried it yet so I can't confirm for myself whether it works. The source is not somebody to give bad advice, I have seen a lot of his work and it is still in great shape after this many years.
Just a thought!

[start2finish]

do you need to add water to make it set up?

this would be an improvement for sure, 3 men including myself took 6 hours to lay 108 feet, this is after digging footers and compacting base, about 2.5 hours.

let me see if I get this right, normal base 2-3'' of mortar (powder not mixed with sand) and set blocks as normal but will be much easier to adjust and let sit for a while, then proceed?

[Matt Kulp]

No, he recomended mixing and laying wet. He said that the mortar goes pretty far when you go that thin. When it is wet it gives you the quick leveling power that saves you the time. We will be trying it with about 1-2" of mud. I think the depth will all depend on how accurate you are with the base. His instructions were to have one guy mixing and spreading, one guy carrying block and third laying.

Hang your string and lay right to it, then move on. It takes a guy about 15 minutes to mix a bag of mud by hand, how long does it take you to level one block on sand?

I will be mixing 3 bags at a shot in a mixer, I figure that should go around 30-35'. I am guesing that 3 guys when up to speed should be able to keep up with one another.

What do you think?

[start2finish]

sounds good, I may try without the mixer first. so you are saying spread the "mud" just like you would laying block. well if you are going this route why not pour a "wet" concrete footing, really wet concrete will almost level itself. now not yet figuring the costs but as a first thought this may work here, our frost line is 12'' footings for a 2 story home are only 18''. and then "hog out" the concrete with the mortar, just a thought,


another thought, this process would be hard to make work when laying a wall around a steep slope where you have several "step-ups" we lay our bottom course and when it runs in the dirt we level our base to line up with the 2nd one. so we would have alot of "downtime", but the old fashioned way would have to work here I guess!

[Matt Kulp]

I don't think that I would use concrete, because the base would become one solid unit, unless you put expansion joint at every block. The whole point of the mortar is that each block is still independent from one another and able to move with the freeze thaw. Concrete would have much bigger sections move and I would think would cause problems.

As far as the step up, I asked the same question of the rep.. He said that if you mix the mud a little thicker in that area it will not be a problem.

[neversatisfiedj]

Ditto - these walls and pavements we lay are FLEXIBLE . remember that. How can it flex in mortar. it CAN"T. That guy should stick to selling materials not installing them.

--Josh

[Busy Bee]

So you are saying to lay mortar under block but on top of your compacted base leaving expansion joints at every block?

[Raj Venugopal]

I'd like to know a bit more Matt.

Lay the crushed rock (minus an inch or so), hang a string level to the top of the desired top of base course elevation, then lay the base course using mortar spread on the bottom as a leveller?

I can see this being a great technique, but Josh's question about not having a flexible wall mirrored my own thinking. In areas with frost heave is this a workable option? My wife and I laid about 100' of base coursing last weekend and I can see how this would be very quick.

Also, the error factor..... Despite best planning, plans change and mistakes are made re final elevations, and base courses have to be built up or down, or change direction. How nasty is this mortared base course to rip out if it binds to the stones beside them?

Is there any risk of the base course settling further into the mortar as it cures?

I'd be interested in seeing some pics, if at all possible.

Very interesting discussion.
Raj

[Matt Kulp]

Think of it like this, the mortar in essence is not binding to anything other then the block above it. So, it acts just like the block is a little bigger then it really is. That block will still be able to move freely from the wrest because the mortar will crack beside the next block when the freeze thaw happens.

As far as the error factor, I don't think it would be a big deal other then chipping some mortar. Not fun, but not a big deal if caught early in the process.

I am not recommending the process until I try it personally and watch it for a year or two. Will it save time, Yes. Is it shown in installation manuals, No. I was simply putting out a idea I have been given by a very experienced installer.

Obviously Josh thinks a bad idea, that's fine.

The walls we install are supposed to flex and move with the freeze cycle, this process will not prohibit any flex in the wall.

Different strokes for different folks, some lay on 2a only, some lay on 3/4 clean only, some lay on sand, some lay on stone dust. This guy laid on a 1" bead of Mortar for a very long time and never had a problem.

[neversatisfiedj]

Try it out and let us know. I just tend to follow a companys R&D but I am open to anything that will net me more $$$. I use to lay on 1/2" of sand but now just lay on wet cr6 base. My walls are perfect but do take time. Good luck.

[AZTLANLC]

I think it makes sense, we personally use a method Paul discussed here, which was to mix 1 part portland 3 parts stone dust and just spread it dry about 1/2" thick on top of the 3/4- base, maybe I will try to use it wet next time just to speed a little more and will report back.